The prior art is replete with numerous examples of rotary hammer driving mechanisms and hammer-drill arrangements and which are useful in construction and mining applications. In high power hammer-drill applications, compressed air driven hammer-drills are frequently employed in view of the high energy that can be delivered by such relatively lightweight man portable devices. However, in these previous prior art assemblies, the compressed air driven hammer-drills are very energy inefficient. In this regard, it has been calculated that these compressed air hammer-drills utilize only on the order of about 20% of the available energy delivered by the compressed air. As should be understood, and for example in commercial mining operations, this inefficiency results in significant power costs. Additionally, distributing a large quantity of compressed air to various work locations, such as in a mine, and other similar environments can require the fabrication of large, complex and expensive air piping systems.
To eliminate the need for compressed air, electric hammer drills have been produced but have had other limitations with respect to the amount of energy percussion that could be delivered. In these prior art arrangements, it has been well known that hammer-drill power is typically the product of the hammer impact energy per blow, and the blow frequency. In this regard, three avenues for increasing hammer effectiveness are available, those being, 1) increasing the hammer velocity, 2) increasing the hammer weight, and/or 3) increasing the hammer blow frequency. From experience there is an upper limit to the hammer velocity beyond which hammer and tool materials begin to fail. Furthermore, to the degree that the hammer weight is increased, the overall weight of the resulting tool and the tool vibration correspondingly increases. Still further, it has been known that increasing the hammer weight typically results in a reduction of the hammer blow frequency. This is due to the fact that as the hammer weight increases, it typically takes more time for the hammer to be reset and readied for another impact in view of the weight and corresponding friction, which acts upon the hammer.
A new and improved percussion tool which addresses these and other shortcomings of the prior art devices is the subject matter of the present application.